Steering system with locking mechanism

ABSTRACT

A steerable device, such as a steerable catheter, may include a control handle and an insertion shaft extending outwardly therefrom. In use, the insertion shaft is navigated to an area of interest for examination and/or treatment thereof. The steerable device may include a steering system that controls the deflection angle of the distal end of the insertion shaft in two or more non-planar directions for navigating the insertion shaft to the area of interest. The steering system may also include a locking mechanism for arresting or partially arresting the movement of the distal end of the insertion shaft in a first direction independent of arresting or partially arresting the movement of the distal end in a second non-planar direction.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.61/052,966, filed May 13, 2008, the disclosure of which is herebyexpressly incorporated by reference.

BACKGROUND

Current medical devices, such as catheters and endoscopes, are employedfor the examination and/or treatment of the mammalian body. Inparticular, various surgical procedures employ a catheter or anendoscope to exam remote parts of the body and/or introduce surgicaltools, fluids or other materials into the body for treatment thereof.For example, in some procedures, catheters and endoscopes may be usedfor the introduction of items including but not limited to radiographiccontrast materials, drugs, angioplasty balloons, stents, fiber opticscopes, laser lights, and cutting instruments (e.g., biopsy forceps, RFcutters, atherectomy devices, etc.), into vessels, cavities,passageways, or tissues of the body.

Navigation of the catheter or endoscope through the vessels, cavities,or passageways of the body to the area of interest is critical to thesuccess of the examination and/or treatment. To this end, moderncatheters and endoscopes include an arrangement that allows the operatorto deflect the distal end of an associated insertion shaft for guidingthe insertion shaft through the passageways, vessels, etc., to the areaof interest. For example, conventional steerable catheters andendoscopes typically comprise a control handle from which an elongatedinsertion shaft extends. The elongated insertion shaft is formed of amaterial or materials of such a stiffness so as to normally maintain theelongated shaft in a straight condition in the absence of an externalforce. The outer end portion of the elongated shaft is relativelyflexible to permit deflection. Pairs of guide wires, also known assteering wires, are connected to the control handle, extend outwardlythrough the elongated shaft, and terminate at the flexible outer endportion of the elongated shaft. A guide wire control mechanism iscarried by the control handle and includes a pair of rotatable controlknobs that cooperate with the respective pairs of guide wires formanually controlling the angular attitude of the flexible outer endportion of the elongated tube to thereby effectively “steer” thecatheter or endoscope in the up/down and right/left directions.

It is also known in the pertinent art to provide the steerable catheteror endoscope with a locking mechanism for arresting the relativedeflection of the elongated shaft during use. In a conventional manner,the control knobs are manually operated to articulate the elongatedshaft in four (4) directions for navigation through a vessel, cavity, orpassageway of a patient. Manual release of the control knobs returns theelongated shaft to its straight condition due to the stiffness of theelongated shaft. At certain points during any particular surgicalprocedure, it may be desired to arrest the relative orientation of theelongated shaft. At such time, the conventional locking mechanism isactivated and movement of both control knobs relative to the remainderof the catheter is simultaneously precluded. For one example of such alocking mechanism, please see co-pending application Ser. No.11/089,380, filed Mar. 23, 2005, which is hereby expressly incorporatedby reference.

While these known locking mechanisms for steerable catheters andendoscopes have proven to be acceptable for their intended applications,they are all associated with limitations. For example, it may bedesirable to accomplish small positional adjustments of the elongatedshaft by allowing only one control knob to effect bending at one timewhile the other knob is locked against rotation. Heretofore lockingmechanisms, however, utilize a single locking lever to simultaneouslyarrest the movement of the both control knobs.

Embodiments of the present invention are directed to steering systems,and in particular, to locking mechanisms that address these limitations.

SUMMARY

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This summary is not intended to identify key features ofthe claimed subject matter, nor is it intended to be used as an aid indetermining the scope of the claimed subject matter.

In accordance with aspects of the present invention, a steering systemis provided for a steerable device having a deflectable insertion shaftthrough which at least first and second steering wires are routed. Thesteering system comprises first and second drive members adapted to becoupled to the first and second steering wires for effecting movement ofthe first and second steering wires, respectively. The steering systemalso comprises a first lock member associated with the first drivemember. The first lock member is movable between an unlocked position,wherein the first drive member is movable to effect movement on thefirst steering wire, and a locked position, wherein the first drivemember is prohibited from effecting movement on the first steering wire.The steering system further comprises a second lock member associatedwith the second drive member and movable independently of the first lockmember. The second lock member is movable between an unlocked position,wherein the second drive member is freely movable to effect movement onthe second steering wire, and a locked position, wherein the seconddrive member is prohibited from effecting movement on the secondsteering wire.

In accordance with another aspect of the present invention, a steeringsystem is provided for a steerable device. The steering system comprisesfirst and second steering wires, first and second drive members coupledto the first and second steering wires for selectively tensioning thefirst and second steering wires, respectively, and first and second lockmembers independently movable between unlocked positions, wherein thefirst and second steering wires are freely movable, and one or morepositions that either restrict or resist movement of the first andsecond steering wires.

In accordance with another aspect of the present invention, a controlhandle of a steering device is provided. The control handle comprises ahandle housing adapted for connection to a deflectable insertion shaftand a steering system carried by the handle housing. The steering systemcomprises first and second drive members adapted for connection to theends of first and second steering wires and a locking mechanism thatlocks the movement of the first drive member independently of the seconddrive member and locks the movement of the second drive memberindependently of the first drive member.

In accordance with another aspect of the present invention, a steerabledevice is provided. The steerable device comprises an elongated shafthaving proximal and distal ends, and a deflectable distal region. Thesteerable device also comprises a control handle functionally coupled tothe proximal end of the elongated shaft and a steering system carried bythe control handle. The steering system is coupled to the distal end ofthe insertion shaft for deflecting the distal end about the deflectabledistal region in at least first and second non-planar directions. Thesteerable device further comprises a locking mechanism that locks thedistal end of the insertion shaft against movement in the firstdirection independently of locking the distal end against movement inthe second direction.

In accordance with another aspect of the present invention, a steerabledevice is provided. The steerable device comprises an elongated shafthaving proximal and distal ends, and a deflectable distal region, acontrol handle functionally coupled to the proximal end of the elongatedshaft, and a steering system carried by the control handle and coupledto the distal end of the insertion shaft for deflecting the distal endabout the deflectable distal region in at least first and second nonplanar directions. The steerable device further includes means forresisting or prohibiting movement of the distal end of the insertionshaft in the first direction while allowing continued deflection of thedistal end of the insertion shaft in the second direction.

DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisinvention will become more readily appreciated as the same become betterunderstood by reference to the following detailed description, whentaken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view of one embodiment of a steerable deviceconstructed in accordance with aspects of the present invention;

FIG. 2 is a cross sectional view of one embodiment of an insertion shaftof the steerable device of FIG. 1;

FIG. 3 is a partial cross sectional view of a control handle depictingone suitable embodiment of a steering system formed in accordance withaspects of the present invention;

FIG. 4 is a partial perspective cut-away view of the control handledepicting the embodiment of the steering system shown in FIG. 3;

FIG. 5 is an exploded view of the steering system shown in FIG. 3;

FIG. 6 is a perspective view of one embodiment of a brake memberconstructed in accordance with aspects of the present invention;

FIGS. 7A and 7B are views depicting a cam member in an unlocked positionand a locked position, respectively; and

FIG. 8 is a top view of an alternative embodiment of the brake memberhoused within a drive member.

DETAILED DESCRIPTION

Embodiments of the present invention will now be described withreference to the drawings where like numerals correspond to likeelements. Embodiments of the present invention are generally directed tosteerable devices of the type having a control handle and a deflectableinsertion shaft that is inserted into a conduit, passageway, body lumen,etc. Several embodiments of the present invention are generally directedto steering systems employed by the steerable devices for controllingthe deflection of the insertion shaft, and in particular, to steeringsystems that comprise a locking mechanism for locking the distal end ofthe insertion shaft at a desired deflection angle. Embodiments of thepresent invention may also be directed to control handles that employsuch steering systems.

Although exemplary embodiments of the present invention will bedescribed hereinafter with reference to a steerable catheter, it will beappreciated that aspects of the present invention have wide application,and therefore, may be suitable for use with many types of medicaldevices, such as endoscopes (e.g., ureteroscopes, duodenoscopes),steerable fiberscopes, steerable guidewires, etc., and non-medicaldevices, such as borescopes. Accordingly, the following descriptions andillustrations herein should be considered illustrative in nature, andthus, not limiting the scope of the present invention, as claimed.

With reference to FIGS. 1-7, there is shown one embodiment of asteerable device, such as a steerable catheter 20, formed in accordancewith aspects of the present invention. As best shown in the embodimentof FIG. 1, the steerable catheter 20 generally includes a control handle22 and an insertion shaft 24 extending outwardly therefrom. In use, theinsertion shaft 24 is navigated through vessels, cavities, passageways,or tissues of a mammalian body to an area of interest for examinationand/or treatment thereof. It will be appreciated that the steerablecatheter 20 may be capable of introducing items, including but notlimited to radiographic contrast materials, drugs, angioplasty balloons,stents, fiber optic scopes, laser lights, cutting instruments (e.g.,biopsy forceps, RF cutters, atherectomy devices, etc.), and otherendoscopic and medical devices (e.g., aspiration and infusion catheters,stone baskets, needles, cytology brushes, snares, ablation devices,etc.) to the area of interest.

As will be described in more detail below, the steerable catheter 20includes a steering system that controls the deflection angle of thedistal end of the insertion shaft 24 in two or more non-planardirections for navigating the insertion shaft 24 through the bodylumens, passageways, etc., to the area of interest. As will be furtherdescribed in detail below, embodiments of the steering system may alsoinclude an exemplary locking mechanism for arresting the movement of thedistal end of the insertion shaft in a first direction independent ofarresting the movement of the distal end in a second non-planardirection.

As best shown in FIG. 1, the insertion shaft 24 can be formed as anelongated body having a proximal end 30 and a distal end 32. Theinsertion shaft 24 may be formed as a hollow tube, a multi-lumenextruded shaft as shown in the cross sectional view of FIG. 2, or otherstructures that permit passage of a plurality of steering wires andoptional instruments, such as biopsy forceps, vision probes, cutters,etc., to the distal end 32. In one embodiment, the insertion shaft 24 iscylindrical with an outer diameter between approximately 4 and 15French, although other diameters may be used. The insertion shaft 24 maybe constructed using various techniques from any suitable material, suchas PEBA® (polyether block amides), nylon, polytetrafluoroethylene(PTFE), polyethylene, polyurethane, fluorinated ethylene propylene(FEP), thermoplastic polyurethane, thermoplastic elastomers and thelike, or combinations and blends thereof.

The insertion shaft 24 is configured so that it is capable of beingdeflected or “steered” through or within the cavities, vessels,passageways, etc. of a body to an area of interest. To that end, theinsertion shaft 24 can be constructed so that it varies in stiffnessbetween the proximal end 30 and the distal end 32. In particular, thedistal region of the insertion shaft 24 can be constructed to be moreflexible than the proximal region. This may allow the insertion shaft 24to be easily advanced without compressing and with minimal twistingwhile providing deflection capabilities for deflecting the distal end32. In some embodiments, the flexibility may be varied gradually (e.g.,increasingly) throughout the length of the insertion shaft from itsproximal end 30 to its distal end 32. In other embodiments, the distalregion of the insertion shaft (e.g., the most distal 1-3 inches of theinsertion shaft) can be made more flexible (i.e., less stiff) than theremainder of the insertion shaft.

In the embodiment shown in FIG. 1, the insertion shaft 24 is comprisedof a proximal section 36, a more flexible deflection section 38positioned distally of the proximal section 36, and a distal tip 40located at the distal end 32. In some embodiments, the deflectablesection 38 is constructed of a material with less stiffness than theproximal section 36. In yet other embodiments, the deflection section 38may be an articulating joint. For example, the deflection section 38 mayinclude a plurality of segments that allow the distal end to deflect intwo or more non-planar directions. For examples of articulation jointsthat may be practiced with embodiments of the present invention, pleasesee co-pending U.S. patent application Ser. Nos. 10/306,149, 10/811,781,and 10/956,007, the disclosures of which are hereby incorporated byreference.

Referring now to FIGS. 1 and 2, the steerable catheter 20 furtherincludes a plurality of steering wires 44 that cause the distal end 32of the insertion shaft 24 to deflect in two or more non-planardirections. In the illustrated embodiment shown in FIG. 2, the steerablecatheter includes two pairs of steering wires 44 spaced approximately 90degrees apart for providing 4-way steering (i.e., up/down/right/left) ofthe insertion shaft 24. In alternative embodiments, the steerablecatheter includes two steering wires 44 that allow the user to steer thedistal end in at least two non-planar directions.

The steering wires 44 are routed, for example, through a correspondingnumber of steering wire lumens of the insertion shaft 24. The lumens maybe positioned within the wall of a tubularly configured shaft, definedby tubes extending through a central bore of the tubular shaft, ordefined by bores 46 of an extruded shaft, as shown best in FIG. 2. Thesteering wires 44 preferably have sufficient tensile strength andmodulus of elasticity so that they do not deform (elongate) duringcurved deflection. In one embodiment, the steering wires are made from304 stainless steel with an 0.008 inch diameter and have a tensilestrength of approximately 325 KPSI. The steering wires 44 may belubricated or may be housed in a PTFE thin-walled extrusion (with orwithout lubricant) to help prevent the insertion shaft from binding upduring deflection, if desired. The steering wires 44 may have any crosssectional geometry; in this embodiment they are round.

The distal ends of the steering wires 44 can be secured at the distalend 32 of the insertion shaft 24 in a conventional manner such thattension applied to the steering wires 44 causes the distal end 32 todeflect in a controllable manner. In embodiments having a discretedistal tip, the steering wires 44 may be anchored to the distal tip ofthe insertion shaft 24 using conventional techniques, such as adhesivebonding, heat bonding, crimping, laser welding, resistance welding,soldering, etc. In one embodiment, the steering wires 44 are attachedvia adhesive bonding, laser welding, resistance welding, soldering orother known techniques to a fluoroscopy marker band (not shown) fixedlyattached to the distal tip 40 of the insertion shaft 24. The steeringwires 44 extend from the distal end 32 of the insertion shaft 24 to theopposing, proximal end 30 of the insertion shaft 24 and terminate in asuitable manner at a steering system carried by the control handle 22,as will be described in detail below.

Returning to FIG. 1, the insertion shaft 24 is functionally connected atits proximal end 30 to the control handle 22. In the embodiment shown,the control handle 22 includes a handle housing 50 formed in oneembodiment by two housing halves 50A-50B joined by appropriate removablefasteners, such as screws, or non removable fasteners, such as rivets,snaps, heat bonding, adhesive bonding, or interference fits (e.g., crushpins, etc.). In the embodiment shown, the proximal end 30 of theinsertion shaft 24 is routed through a strain relief fitting 52 securedat the distal end of the handle housing 50. The handle housing 50 mayinclude other features, if desired, such as one or more ports forproviding access to optional channels of the insertion shaft 24. Forexample, the ports may include one or more of the following: an imagingdevice port 54; a working channel port 56; and an irrigation/suctionport 58.

As best shown in FIG. 3-5, the handle housing 50 carries one suitableembodiment of a steering system, generally designated 60, which isconstructed in accordance with aspects of the present invention. In use,a physician or technician manually operates the steering system 60 forcontrolling the deflection of the distal end 32 of the insertion shaft24 as the insertion shaft is advanced through vessels, passageways,etc., to an area of interest. Embodiments of the steering system 60include two movable members that are operatively connected to the distalend of the insertion shaft via steering wires 44. In the embodimentshown, the movable members are control knobs 62 and 64, which areconnected to two pairs of steering wires 44 for effecting 4-way steeringof the distal end 32 of the insertion shaft 24 in the up/down directionand in the right/left direction. For example, the first control knob 62is connected to a pair of steering wires 44 to control up/down steeringand the second control knob 64 is connected to a pair of steering wires44 to control right/left steering. Alternatively, other movable membersmay by employed, such as steering dials, linear sliders, etc., forsteering the distal end of the insertion shaft 24. In other embodiments,a single steering wire 44 may be coupled to each of the movable members,such as the first and second control knobs 62 and 64. In theseembodiments, it will be appreciated that the termination locations ofthe wires determine the directions in which the insertion shaft maydeflect.

The steering system 60 further includes first and second drive members66 and 68, which are interconnected between the first and second controlknobs 62 and 64 and the pairs of steering wires 44. As best shown inFIG. 5, each drive member 66 and 68 is an integrally formed piece ofmaterial, such as plastic, defining a truncated or semi-circular pulley70 on one side and an outwardly extending rim 72 on the other. While inthe embodiment shown the rim 72 forms a hollow cylinder, the rim 72 maybe alternatively configured with one of more spaced apart arcuatesections. As will be described in detail below, the rim 72 functionslike a brake drum defining one or more braking surfaces against whichportions of the locking mechanism act to arrest or partially arrestrotation of the drive members.

Still referring to FIGS. 3-5, the first drive member 66 can beintegrally formed or keyed for rotation with one end of a cylindricaldrive shaft 76. The other end of the drive shaft 76 can be keyed orotherwise attached to the first control knob 62 for co-rotation.Likewise, the second drive member 68 can be integrally formed or keyedfor rotation with one end of a second cylindrical drive shaft 78. Theother end of the drive shaft 78 can be keyed or otherwise attached tothe second control knob 64 for co-rotation. When assembled, the proximalends of a first pair of steering wires 44 can be secured to oppositesides of the pulley 70 of the first drive member 66 in a conventionalmanner. Likewise, the proximal ends of a second pair of steering wires44 are secured to opposite sides of the pulley 70 of the second drivemember 68 in a conventional manner. As a result, rotation of the controlknobs 62 and 64 rotates the drive members 66 and 68, which in turn,applies tension to the steering wires 44 for deflecting the distal endof the insertion shaft 24 to a desired deflection angle.

In accordance with aspects of the present invention, the steering system60 may further include a locking mechanism that functions to lock orpartially lock the distal end of the insertion shaft 24 in a desireddeflection position or angular attitude during use. For example, severalembodiments of the locking mechanism can be configured to lock theposition of the distal end of the insertion shaft in a first directionindependently of movement of the distal end in a second non-planardirection. Stated differently, several embodiments of the lockingmechanism can be configured to arrest the movement of the distal end ofthe insertion shaft in one direction while allowing it to move in asecond non-planar direction. This may be desirable for providing moreoperator control to effect the desired angular attitude of the distalend for proper guidance through the vessel, passageway, etc.

This can be accomplished by, for example, arresting the movement of thefirst and/or second control knobs 62 and 64, by arresting the movementof the first and/or second drive members 66 and 68, or arresting themovement of the first and/or second pairs of steering wires 44associated with the control knobs 62 and 64. As will be described indetail below, one embodiment of the locking mechanism shown in FIGS. 1and 3-7B arrests the movement of the first and second drive members 66and 68 by, for example, impeding the rotation thereof. However, othertechniques of arresting the movement of the control knobs, the drivemember, the steering wires, or combinations thereof are contemplated tobe within the scope of the present invention, as defined by the claims.

Thus, by arresting the movement of the drive members 66 and 68independently, the distal end of the insertion shaft can be locked frommovement in one direction while allowing continued deflection of thedistal end of the insertion shaft in a second non-planar direction. Aswill be described in detail below, embodiments of the lock mechanism mayapply resistive forces for partially locking the position of the distalend of the insertion in one or more non-planar directions.

Referring now to FIGS. 3-7B, one embodiment of the locking mechanismsuitable for use in the steering system 60 will be described in detail.As best shown in FIG. 3-6, the locking mechanism comprises first andsecond locking devices. The first and second locking devices comprisefirst and second cam members 84 and 86, first and second lock members,such as lock levers 90 and 92, and first and second brake members 96 and98, respectively. The first and second brake members 96 and 98 and thefirst and second cam members 84 and 86 cooperatively function viamovement of the first and second lock levers 90 and 92, respectively, torestrict movement, i.e., rotation, of the first and second drive members66 and 68.

As best shown in FIGS. 5 and 6, the brake members 96 and 98 eachcomprise a generally circular ring 102 as its base having one or moreinwardly projecting tabs 104 spaced around the inner perimeter thereof.The brake members 96 and 98 further include one or more brake arms 106that are attached at one end to the top surface of a respective tab 104and extend in a cantilevered manner to a free end 110. In the embodimentshown in FIG. 6, the one or more brake arms 106 include three brakearms, which are positioned in a plane parallel to and adjacent the ring102. The brake arms 106 extend around the ring in manner shown in FIG.6.

The brake members 96 and 98 are constructed from a suitable material orcombination of materials, such as plastic or various metals, whichallows the cantilevered brake arms 106 to flex outwardly for interactionwith the inner rim 72 when force is applied and to return to theirunflexed position upon removal of the applied force. The ring 102further includes notches 112 around its perimeter for interfacing withstructure within the handle housing for preventing rotation of the brakemember when assembled.

As best shown in FIG. 6, each brake arm 106 defines a braking surface116 at the exterior surface of the free end 110. In the embodimentshown, the brake surfaces 116 are configured with a convex geometry forcooperating with the inner surface of the rim 72. The braking surfaces116 may be textured, coated with high fiction materials, etc., toenhance the braking effect. The brake arms 106 further define camsurfaces 120 along their interior surfaces. The cam surfaces 120 areconfigured with a geometry such that as the cam surfaces extend from thefixed end 108 of the brake arms 106 to a position in proximity of thefree end 110, the cam surface 120 gradually progresses radially inwardlyto the center of the cavity 136. It will be appreciated that the numberof brake arms 106, the size and geometry of the cam surfaces and brakesurfaces, etc., can vary to effect more or less braking force,depending, for example, on the intended application.

Referring to FIG. 6, the beginning and ending of the cam surfaces 120can be formed with detent notches 122A and 122B, respectively, whichcooperate with a portion of the cam member for providing indexedmovement between locked and unlocked positions. In an alternativeembodiment shown in FIG. 8, one or more detent notches 122C, 122D, etc.,can be formed in the cam surfaces 120 between the detent notches 122Aand 122B for providing one or more partial locking positions that applyvarying (e.g., increasing) braking forces to the drive members. Thisallows the drive members to rotate against a selected resistance, whichmay aid, for example, in precision steering of the distal end. As such,the locking member can move from the unlocked position to one or more ofthe partial locking positions, which applies a partial braking force(i.e., one that resists rotation of the drive member), or to the lockedposition, also referred to as the fully locked position, which applies afull braking force (i.e., one that prohibits rotation) on the drivemember.

Referring now to FIGS. 5, 6 and 7A-B, each cam member 84 and 86 caninclude a plurality of cams 130 for interacting with the cam surfaces120 of the brake members 96 and 98. It will be appreciated that thenumber of cams 130 corresponds to the number of brake arms 106. In theembodiment shown, the cam members 84 and 86 each comprise a cylindricalhub 132 from which the cams 130 outwardly extend. The cam members 84 and86 are cooperatively sized to be rotatingly received within the cavity136 defined by the brake members 96 and 98 such that the cams 130contact the cam surfaces 120 in the manner shown in FIGS. 7A-7B.

As best shown in FIGS. 4 and 6, the first cam member 84 can beintegrally formed or keyed for rotation with one end of a cylindricaldrive shaft 140. The other end of the drive shaft 140 can be keyed orotherwise attached to the first lock lever 90 for co-rotation.Similarly, the second cam member 86 can be integrally formed or keyedfor rotation with one end of a cylindrical drive shaft 142. The otherend of the drive shaft 142 can be keyed or otherwise attached to thesecond lock lever 92 for co-rotation. As a result, rotation of the firstand second lock levers 90 and 92 can rotate the first and second cammembers 84 and 86 within the first and second brake members 96 and 98,respectively, thereby causing the cams 130 of the first and second cammembers 84 and 86 to interact with the brake arms 106 of the first andsecond brake members 96 and 98.

Turning now to FIG. 3, the steering system 60 is shown in its assembledstate for operation by a user to selectively deflect the distal end ofthe insertion shaft, and to lock the distal end against movement in oneor more directions. As assembled, the first brake member 96 is mountedin a non-rotational manner to structure of the housing half 50B. Thefirst cam member 84 is rotationally supported within the housing via itsinner bore 146, which receives a fixed shaft 148 integrally formed orotherwise positioned to extend into the interior of the housing half50B. When rotationally supported in the housing, the first cam member 84is received within the cavity of the first brake member 96 andcooperates therewith such that the cams of the first cam member 84interface with the cam surfaces of the brake arms 106.

Continuing to described the assembled state of the steering system 60,the first drive member 66 is rotationally supported over the drive shaft140 of the cam member 84 for independent rotation with respect to thefirst cam member 84. The first drive member 66 can be positioned suchthat its rim 72 extends around the perimeter of the brake arms 106. Thesecond drive member 68 is rotationally supported over the drive shaft 76of the first drive member 66 for independent rotation with respect tothe first drive member 66. As assembled, the first drive member 66should be spaced apart from the second drive member 68 so that one doesnot interfere with rotation of the other.

The second cam member 86 can be rotationally supported over the driveshaft 78 of the second drive member 68 for independent rotation withrespect to the second drive member 78. Similar to the first brake member96, the second brake member 98 can be mounted in a non-rotational mannerto structure of the housing half 50A. When rotationally supported in thehousing by the drive shaft 78, the second cam member 86 can be receivedwithin the cavity of the second brake member 98 and cooperates therewithsuch that the cams of the second cam member 86 interface with the camsurfaces of the brake arms 106. The second drive member 68 can befurther positioned such that its rim 72 extends around the perimeter ofthe brake arms 106 of the second brake member 68.

Still referring to FIG. 3, the ends of the drive shafts 76, 78, 140, and142 associated with the first drive member 66, the second drive member68, the first cam member 84, and the second cam member 86, respectively,extend through an opening in the housing half 50A in a rotationallysupported manner and outwardly of the housing half 50A. The firstcontrol knob 62, the second control knob 64, the first lock lever 90 andthe second lock lever 92 are attached in a suitable manner to the driveshafts 76, 78, 140, and 142, respectively, for co-rotation.

One method of operating an embodiment of the steerable catheter 20 willnow be described with reference to FIGS. 1-7B. First, the operatorinserts the insertion shaft 24 into a conduit with the lock levers 90and 92 in the unlocked positions. As the operator advances the insertionshaft 24 into the conduit, vessel, passageway, body lumen, etc., theoperator can manipulate the first and second control knobs 62 and 64independently to “steer” the distal end 32 of the insertion shaft 24 tothe area of interest. When the operator wishes to lock the distal end 32from deflective movement in one direction, while allowing the distal end32 to deflect in another non-planar direction, the operator can activatethe lock lever corresponding to the drive member that effects steeringin that specific direction. For example, if the operation wishes to lockthe distal end 32 from deflective movement in the up or down direction,the operator can move the lock lever 90 from its unlocked position toits locked position.

By moving the lock lever 90 from the unlocked position to the lockedposition, the cam member 84 associated with the lock lever 90 can movefrom the unlocked position shown in FIG. 7A to the locked position shownin FIG. 7B. In the unlocked position of FIG. 7A, the cams 130 arepositioned within the notches 122A at the beginning of the cam surfaces120, and the brake surfaces 116 of the brake arms 106 are free fromengagement with the rim 72 of the drive member 66. When the cam member84 rotates in the direction of the arrow to the position shown in FIG.7B, the cams 130 follow the cam surfaces 120 of the brake arms 106 tothe notches 122B at the end of the cam surfaces 120. Due to theconfiguration of the cam surfaces 120, the cams 130 force the brake arms106 outwardly in such a manner that the brake surfaces 116 of the brakearms 106 frictionally engage the rim 72 of the drive member 66, therebyarresting rotation of the drive member 66.

In the locked position of FIG. 7B, the drive member 66 is precluded fromrotation, which in turn, precludes movement of the distal end 32 of theinsertion shaft 24 in the up/down direction. The distal end 32, however,is still free to move, i.e., deflect, in the left/right direction byrotation of control knob 64. If the operator wishes the lock the distalend 32 from deflective movement in the right or left direction, theoperator can then move the lock lever 92, which is associated with thecam member 86 and drive member 68, from the unlocked position to thelocked position.

If the operator subsequently desires to continue steering the distal end32 of the insertion shaft 24 by changing the deflection angle of thedistal end 32 from its current position to another position, one or bothof the lock levers 90, 92 can be moved from the locked position to theunlocked position. This, in turn, rotates the cam members with respectto the drive members. Again, due to the configuration of the camsurfaces 120 of the brake arms 106, and the flexure thereof, the brakesurfaces 116 of the brake arms 106 are removed from contact with therims 72 of the brake members. This alleviates the friction between thebrake surfaces 116 of the brake arms 106 and the rims 72 of the drivemembers 66 and 68, thereby allowing the first and second drive members66 and 68 to rotate by turning the control knobs 62 and 64.

Embodiments of the locking mechanism thus far have been shown anddescribed to include two substantially similar locking devices (i.e.,locking member/cam member/brake member) to arrest or partially arrestthe movement of the drive members. It will be appreciated thatembodiments of the locking mechanism need not be so limiting. Forexample, alternative embodiments of the locking mechanism may employother locking devices, including conventional or future developedlocking devices, for arresting or partially arresting one or both of thedrive members 66 and 68.

Other locking devices that may be practiced with embodiments of thelocking mechanism, and thus, are within the scope of the presentinvention, as claimed, may include but are not limited to set screws,sliding pins, or the like, which are appropriately carried by the handlehousing 50. In several embodiments, the set screw or sliding pin can beconfigured and arranged for selectively engaging a portion of anassociated drive member. For example, the set screw or sliding pin mayengage a threaded or non-threaded bore or like structure disposed in theassociated drive member or may abut against a cooperating side face ofthe truncated pulley (acting as a rotational stop) for prohibitingmovement (e.g., rotation) of the drive member.

In other embodiments, the end of the set screw may apply a braking forceagainst a face of the drive member for arresting or partially arrestingthe movement of the drive member. It will be appreciated that the end ofthe set screw may be configured with an end surface that is larger thanits threaded shaft, and may include texturing, friction coating, etc.,to enhance the applied braking force. Of course, the locking mechanismcan employ any combination of the locking devices described herein orknown or future developed locking devices for arresting or partiallyarresting the control knobs, the drive members, the steering wires, orcombinations thereof.

While illustrative embodiments have been illustrated and described, itwill be appreciated that various changes can be made therein withoutdeparting from the spirit and scope of the invention, as claimed. Forexample, while embodiments of the steering system have been described asnot including steering wires, it will be appreciated that steering wiresmay be included in the steering systems of the present invention.

The invention claimed is:
 1. A steering system for a steerable devicehaving a deflectable insertion shaft through which at least first andsecond steering wires are routed, the steering system comprising: firstand second drive members having an axis of rotation and adapted to becoupled to the first and second steering wires for effecting movement ofthe first and second steering wires, respectively; a first lock memberassociated with the first drive member, the first lock member moveablebetween an unlocked position, wherein the first drive member is freelymovable to effect movement on the first steering wire, and a lockedposition, wherein the first drive member is prohibited from effectingmovement on the first steering wire; and a second lock member associatedwith the second drive member and movable independently of the first lockmember, the second lock member movable between an unlocked position,wherein the second drive member is movable to effect movement on thesecond steering wire, and a locked position, wherein the second drivemember is prohibited from effecting a movement on the second steeringwire; wherein the first lock member includes a first brake armconfigured to deflect radially outwardly relative to the axis ofrotation when the first lock member is moved to lock the first drivemember; and wherein a frictional engagement between a radially outwardfacing surface of the first brake arm and a radially inward facingsurface of the first drive member causes a radially directed forcesufficient to arrest movement of the first drive member, furthercomprising a first cam member having a first cam configured to engagewith a first notch on the first brake arm, wherein rotation of the firstcam member causes the first brake arm to deflect radially outward. 2.The steering system of claim 1, further comprising first and secondlevers coupled for co-action with the first and second drive members,respectively.
 3. The steering system of claim 2, wherein the first andsecond levers are control knobs.
 4. The steering system of claim 1,further comprising first and second brake members configured torespectively prohibit the first and second drive members from effectingmovement of the first and second steering wires.
 5. The steering systemof claim 4, further including a second cam member connected forco-action with the second lock member, the first and second cam membersinteracting with the first and second brake members, respectively, forprohibiting the first and second drive members from effecting movementof the first and second steering wires.
 6. The steering system of claim5, wherein the first brake member includes the first brake arm and thesecond brake member includes a second brake arm configured to deflectradially outwardly relative to the axis of rotation when the second lockmember is moved to lock the second drive member and having a radiallyoutward facing surface, wherein the radially outward facing surface ofeach of the first and second brake arms is configured to move intoengagement with a respective one of the first radially inward facingsurface of the first drive member and a second radially inward facingsurface of the second drive member when interacting with the first andsecond cam members, respectively.
 7. The steering system of claim 6,wherein each of the first and second lock members includes at leastthree brake arms configured to deflect radially outwardly relative tothe axis of rotation.
 8. The steering system of claim 1, wherein atleast one of the first and second lock members are lock levers or aportion of a brake member.
 9. The steering system of claim 1, whereinmovement of the first and second lock members cause contact against arespective one of the first and second drive members in a mannersufficient to arrest movement thereof.
 10. The steering system of claim6, wherein each of the first and second brake arms defines a camsurface, and wherein the second cam member includes a cam thatcorresponds with the second brake arm and interfaces with the camsurface of the second brake arm.
 11. The steering system of claim 10,wherein movement of the first and second cam members cause the cams tofollow the cam surfaces, thereby forcing the radially outward facingsurfaces of the first and second brake arms into contact with arespective one of the radially inward facing surfaces of the first andsecond drive members.
 12. The steering system of claim 11, wherein eachof the cam surfaces includes a notch located at the ends of the camsurfaces, the notches being associated with an unlocked and a lockedposition of a respective one of the first and second drive members. 13.The steering system of claim 12, wherein each of the cam surfacesincludes one or more notches between the ends of the cam surfaces, theone or more notches being associated with one or more partially lockedpositions of a respective one of the first and second drive members. 14.A steering system for a steerable device, comprising: first and secondsteering wires; first and second drive members having an axis ofrotation and coupled to the first and second steering wires forselectively tensioning the first and second steering wires,respectively; first and second lock members independently movablebetween unlocked positions, wherein the first and second steering wiresare freely movable, and one or more positions that either restrict orresist movement of the first and second steering wires; wherein thefirst lock member includes a first brake arm configured to deflectradially outwardly relative to the axis of rotation when the first lockmember is moved to lock the first drive member; and wherein a frictionalengagement between a radially outward facing surface of the first brakearm and a radially inward facing surface of the first drive membercauses a radially directed force sufficient to arrest movement of thefirst drive member, further comprising a first cam member having a firstcam configured to engage with a first notch on the first brake arm,wherein rotation of the first cam member causes the first brake arm todeflect radially outward.
 15. The steering system of claim 14, whereinthe movement of at least one of the first and second lock members isindexed.
 16. The steering system of claim 14, wherein one of the one ormore positions is selected from a group consisting of a locked position,wherein movement of the associated steering wire is restricted, and apartially locked position, wherein movement of the associated steeringwire is resisted.
 17. A control handle of a steering device, the controlhandle comprising: a handle housing adapted for connection to adeflectable insertion shaft through which at least first and secondsteering wires are routed; a steering system carried by the handlehousing, the steering system comprising: first and second drive membersadapted for connection to the ends of the first and second steeringwires and having an axis of rotation; a locking mechanism that locks themovement of the first drive member independently of the second drivemember and locks the movement of the second drive member independentlyof the first drive member, wherein the locking mechanism includes afirst brake arm configured to deflect radially outwardly relative to theaxis of rotation when the locking mechanism is moved to lock the firstdrive member; and wherein a frictional engagement between a radiallyoutward facing surface of the first brake arm and a radially inwardfacing surface of the first drive member causes a radially directedforce sufficient to arrest movement of the first drive member; and afirst cam member having a first cam configured to engage with a firstnotch on the first brake arm, wherein rotation of the first cam membercauses the first brake arm to deflect radially outward.
 18. The controlhandle of claim 17, wherein the locking mechanism includes first andsecond locking members configured to engage with the first and seconddrive members, respectively.
 19. A steerable device, comprising: anelongated shaft having proximal and distal ends, and a deflectabledistal region; a control handle functionally coupled to the proximal endof the elongated shaft; a steering system having an axis of rotation,carried by the control handle, and coupled to the distal end of theelongated shaft for deflecting the distal end about the deflectabledistal region in at least first and second non-planar directions; firstand second drive members rotatably mounted about the axis of rotation;and a locking mechanism that locks the distal end of the elongated shaftagainst movement in the first direction independently of locking thedistal end of the elongated shaft against movement in the seconddirection, wherein the locking mechanism includes a first brake armconfigured to deflect radially outwardly relative to the axis ofrotation when the locking mechanism is moved to lock the first drivemember; and wherein a frictional engagement between a radially outwardfacing surface of the first brake arm and a radially inward facingsurface of the first drive member causes a radially directed forcesufficient to arrest movement of the first drive member, furthercomprising a first cam member having a first cam configured to engagewith a first notch on the first brake arm, wherein rotation of the firstcam member causes the first brake arm to deflect radially outward. 20.The steerable device of claim 19, wherein the first and second drivemembers of the steering system are movably mounted to the controlhandle, and at least first and second steering wires are routed throughthe elongated shaft and coupled between the first and second drivemembers and the distal end of the elongated shaft.
 21. The steerabledevice of claim 20, wherein each of the first and second drive membersare rotationally mounted about the axis of rotation, and wherein thesteering system further includes first and second control knobsconnected to the first and second drive members, respectively, forco-rotation.
 22. The steerable device of claim 20, wherein the lockingmechanism includes a first lever movable between an unlocked positionand a locked position, a first brake member, and the first cam memberbeing cooperatively associated with the first brake member such thatmovement of the first lever from the unlocked position to the lockedposition causes the first cam member to force the radially outwardfacing surface of the first brake member into abutment against theradially inward facing surface of the first drive member.
 23. Thesteerable device of claim 22, wherein the locking mechanism furtherincludes a second lever having a radially outward facing surface andmovable between an unlocked position and a locked position, a secondbrake member configured to deflect radially outwardly relative to theaxis of rotation when the locking mechanism is moved to lock at leastthe second drive member having a radially inward facing surface, and asecond cam member cooperatively associated with the second brake membersuch that movement of the second lever from the unlocked position to thelocked position causes the second cam member to force a radially outwardfacing surface of the second brake member into abutment against theradially inward facing surface of the second drive member.
 24. Thesteerable device of claim 19, further including first and second pairsof steering wires routed through the elongated shaft, the ends of whichterminate at the distal end of the elongated shaft in a manner as toeffect 4-way steering of the distal end of the elongated shaft; whereinthe first and second drive members are rotatably supported about theaxis of rotation by the control handle and coupled to the proximal endsof first and second pairs of the steering wires, respectively, andfurther including first and second control knobs coupled for co-rotationwith the first and second drive members respectively, wherein rotationof the control knobs effect 4-way steering of the distal end of theelongated shaft.
 25. A steerable device, comprising: an elongated shafthaving proximal and distal ends, and a deflectable distal region; acontrol handle functionally coupled to the proximal end of the elongatedshaft; a steering system having an axis of rotation and including firstand second drive members rotatably mounted about the axis of rotation,carried by the control handle, and coupled to the distal end of theelongated shaft for deflecting the distal end about the deflectabledistal region in at least first and second non planar directions; and alocking mechanism configured to prohibit movement of the distal end ofthe elongated shaft in the first direction while allowing continueddeflection of the distal end of the elongated shaft in the seconddirection, wherein the locking mechanism includes a first brake armconfigured to deflect radially outwardly relative to the axis ofrotation when the locking mechanism is moved to lock the first drivemember; wherein a frictional engagement between a radially outwardfacing surface of the first brake arm and a radially inward facingsurface of the first drive member causes a radially directed forcesufficient to arrest movement of the first drive member; and a first cammember having a first cam configured to engage with a first notch on thefirst brake arm, wherein rotation of the first cam member causes thefirst brake arm to deflect radially outward.